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Microprogram Assemblers for Bit Slice Microprocessors

IP.com Disclosure Number: IPCOM000131336D
Original Publication Date: 1978-Jul-01
Included in the Prior Art Database: 2005-Nov-10
Document File: 14 page(s) / 54K

Publishing Venue

Software Patent Institute

Related People

V. Michael Powers: AUTHOR [+4]

Abstract

[Figure containing following caption omitted: Designers of high-speed microprocessors need good software to help them construct the microprogram, but the seven bit-slice assemblers surveyed here remain essentially low level and even primitive.] One popular class of microcomputer devices consists of high- speed circuit chips, several of which are required to form a complete processor. These ";bit-slice"; devices must be strung together with careful attention to logical and timing detail. The sequence of internal, register-level operations necessary to complete a function step is usually controlled through a sequence of bit patterns retrieved from a memory by a sequence controller. The definitions of sequences and functions stored in this memory comprise a ";microprogram.";'

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

This record contains textual material that is copyright ©; 1978 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Contact the IEEE Computer Society http://www.computer.org/ (714-821-8380) for copies of the complete work that was the source of this textual material and for all use beyond that as a record from the SPI Database.

Microprogram Assemblers for Bit Slice Microprocessors

V. Michael Powers

Oregon State University

Jose H. Hernandez

Advanced Micro Devices*

(Image Omitted: Designers of high-speed microprocessors need good software to help them construct the microprogram, but the seven bit-slice assemblers surveyed here remain essentially low level and even primitive.)

One popular class of microcomputer devices consists of high- speed circuit chips, several of which are required to form a complete processor. These "bit-slice" devices must be strung together with careful attention to logical and timing detail. The sequence of internal, register- level operations necessary to complete a function step is usually controlled through a sequence of bit patterns retrieved from a memory by a sequence controller. The definitions of sequences and functions stored in this memory comprise a "microprogram."'

Completion of a good design with bit-slice chips requires the mastery of an enormous amount of detail, including selection, placement, and connection of the chips as well as choice of the functions and bit patterns of the microprogram. Just as in other fields of computer design, the designer needs good support tools.

1

A single microprogram memory word (a microinstruction) may be as much as 100 bits long, and a microprogram may easily consist of 1000 words or more. The designer needs the tools to control the formation of these bit patterns and to specify them for building and later maintenance. A natural choice of tool is a computer program: first just to count, collate, and record; next to translate mnemonic codes and labels; and then perhaps to choose and generate subsequences of program. But designers of bit-slice processors are concerned equally as much with the chips and their connections (hardware) as they are with the patterns of control bits (software or, when realized in read-only memory, firmware); they cannot afford an inordinately cumbersome translation program. It is especially important that the controls and mechanics of the program not dominate the design process.

Microprogrammed bit slice microprocessors

The manufacturing technology of large-scale integrated circuitry continues to advance, but it has limitations which are likely to remain far into the future. The most popular microprocessors today use some variant of metal oxide semiconductor circuitry, which allows densely packed patterns of gates burning small amounts of power. MOS circuits allow economical yields with a chip

1 *Jose H. Hernandez, currently with Four-Phase...